Terry Paul, Baron John A, Bergkvist Leif, Holmberg Lars, Wolk Alicja
Department of Medical Epidemiology, Karolinska Institutet, Stockholm, Sweden.
Nutr Cancer. 2002;43(1):39-46. doi: 10.1207/S15327914NC431_4.
Although laboratory data and a few adenoma prevention trials suggest that calcium supplementation may reduce the risk of colorectal neoplasia, the results of observational studies of calcium intake and colorectal cancer risk are contradictory. However, few studies have examined the association among women or effects in specific colon subsites. Women with colorectal cancer diagnosed through 31 December 2000 were identified by linkage to regional cancer registries. During an average 11.3 yr of follow-up of 61,463 women, we observed 572 incident cases of colorectal cancer. Using data obtained from a 67-item food frequency questionnaire and Cox proportional hazards models to estimate rate ratios and 95% confidence intervals, we found an inverse association between dietary calcium intake and colorectal cancer risk. Women with the highest calcium intake (median 914 mg/day) had a reduced risk of colorectal cancer (rate ratio = 0.72, 95% confidence interval = 0.056-0.93, P for trend = 0.02) compared with women with the lowest intake (median 486 mg/day). Furthermore, our results suggest that the inverse association may be strongest in relation to distal cancers and among older women. The association with dairy products was less clear, suggesting that calcium intake per se is more important than specific calcium sources. Vitamin D intake was not clearly associated with risk. In sum, our data suggest that high calcium intake may lower colorectal cancer risk.
尽管实验室数据和一些腺瘤预防试验表明，补充钙可能会降低结直肠肿瘤的风险，但关于钙摄入量与结直肠癌风险的观察性研究结果相互矛盾。然而，很少有研究考察过女性群体中的这种关联或特定结肠亚部位的影响。通过与地区癌症登记处建立联系，识别出在2000年12月31日前被诊断为结直肠癌的女性。在对61463名女性平均11.3年的随访期间，我们观察到572例结直肠癌新发病例。利用从一份包含67个条目的食物频率问卷中获得的数据以及Cox比例风险模型来估计率比和95%置信区间，我们发现膳食钙摄入量与结直肠癌风险之间存在负相关。与钙摄入量最低（中位数为486毫克/天）的女性相比，钙摄入量最高（中位数为914毫克/天）的女性患结直肠癌的风险降低（率比 = 0.72，95%置信区间 = 0.56 - 0.93，趋势检验P值 = 0.02）。此外，我们的结果表明，这种负相关在远端癌症患者和老年女性中可能最为明显。与乳制品的关联不太明确，这表明钙本身比特定的钙来源更重要。维生素D摄入量与风险没有明显关联。总之，我们的数据表明，高钙摄入量可能会降低结直肠癌风险。
